Pulp stock thickener



Nov. 18, 1958 R. WELLS PULP s'rocxTHICKENERv Filed nec. s1, 195eINVENTOR BY ik ATTORNEY AThis invention relates to apparatus 'for'separating Vex- Inthe'inah'ufaeture "et 'paperinii "many molded pulparticles, such as4 egg eiton's, 'pie plates, 'and 'the like,

Hit is "customary/'to employ ap'ulp slurry comprising a "dilutegliquids`1`1's'pe'sio`nV of Vpulpbers ya'sfthepulp stock :in suctionlrnoldingnpera'tins to produce the pulp articles desired. Frequently, it isWnecessary Atothik'e'n the pulp 'slurry, by separating'excessliquid'r'om the lpulp iibers, incident to Ivarious washingoper'ationsand changes in chemical treating agents, during the preparatorytreatment of the pulp stock. A thickeningtrea'trnent may also beemployed in the recoveryfof waste pulp from the so- A'called lwhiteliquor or mill 'eiuent Heretofore, the type of y apparatus'employed'rnost frequently fory thickening 'the pulp stock ,has been vaforaminous'suction roll mounted rotatably partially submerged in apulpslurry tank and connected by suitable ypipesto a Vsuction pump.V TheYapplication of suction to the roll causes wet pulp -fibers to beextracted from the rpulp slurry and depositsthese `fibers in a'layer onthe ysurface of the roll.l This'layer offpulpiibers isv advancedcontinuously during rotation ,of theuroll to a doctor blade or a brushvtype take-oil, roll mounted adjacent to an apronwhere thebers are washedinto a container by a H suitable spray of water. 'I he thickeningapparatus known heretoforerequired complicatediequipment which wasexpensive toinstall and operate.

An object ofI the present invention `is` to provide new -and improvedapparatus for thickening ,pulp stock.

Anotherobjectof the linvention is to-provrde a-simplilied vacuumlessapparatus for separating excess liquid from librous suspensions. l l jStill another vobject-of,the'inventionvis to provide a 'simpliedapparatus for thickening pulp stock and wash- -ing the pulp berstherefrom withoutemploying auxiliary spraying equipment. 1 v 4 y Otherobjects 'and-the Inature'and advantages of the invention. will beapparent from the following descripyti'on'taken in conjunction ,withthev accompanying drawing, .wherein .United Safes Peten-f o The singleligure is-aschematic showing'in vertical sec- I e' tional view` of apulp 4stockthickening apparatus embodying the invention. i

'The apparatus villustrated includes a 4massive, e cylindrical, spongyrtype roll `1 -havingia solid lmetallimcore 2 `ijournalled forrotation-inthe :side walls of van'open tank 3 containing pulpfslurry,This fpulp slurry'may contain, for example, from about 1% to about 3%by'fweight of pulp bers Vsuspended inwater.y They roll1 is mountedpartially submerged in thelpulp'slurry, rand during rota- "tionof'the'roll successive portions thereof-:are advanced "through theslurry for the purpose of absorbing the liquid therefrom r'The spongy.roll 1-1 composed yofa suitableabsorbent `resilient material, such assponge rubber. Either natural rubber in cellular form, or syntheticfoamed rubbery materials may be used, such as lpolyurethane foam. In anyevent, the roll 1 must be durable, resilient, tough, and "capable ofabsorbing a relatively large quantity of liquid. The roll 1 may be builtaround the core 2 by inserting the core into a large cylindrical body ofsponge rubber, or by wrapping a thick sheet of sponge rubber around thecore, vor by securing a series of spongy pads to the periphery of thecore.

A compression or squeezevroll 4 isjournalle'd for rotation in the sidewalls of the tank 3, at approximatelyy the upper level of the pulpAslurry contained therein, 'and in compressing engagement with thespongy roll 1 alongr the entire length thereof. Duringl rotation of thespongyroll 1 the squeeze roll 4 is rotated therewith, due to thefrictional contact between these rolls. As the result of this motion,successive portions of the periphery of the spongy Vroll 1 arecompressed as they` enter the pulp slurry, and -these portions areallowed to re-expand beneath the surface of the slurry, thereby suckingliquid from the slurry bya sponging action. The cellular structure ofthe spongy roll 1 should'be sufficiently line to cause the pulp bers tobe deposited in a thick layer 5 on the periphery of the 1 roll 1, whilethe liquid extracted therefrom is sucked into the interior ofrthis rollduring re-expansion of the compressedt portions thereof.

fAfter'the re-expanded portions of the periphery of the vspongy -roll 1have advanced through an arc of about 1270 beyond the squeeze roll '4,they are again compressed by a take-off roll 6 mounted rotatably incompressing contact with the roll 1 along the entire length thereof. Thetake-oil'roll 6 indents the spongy roll 1 sufficiently to squeeze asmall portion of the water therefrom. The water expressed by thetake-oil roll 6 washes off the layer 5 of pulp fibers deposited on theperiphery of the roll 1. A doctor blade 7 scrapes the wet pulp bersfromthe take-oit roll 6, from whence the pulp "bers'slide down aninclined apron 8 into a suitable chest '9. The wet pulp stockdischargedinto the chest 9 may containfrom about 50% to about 80% by weight of"pulp fibers.

The successively compressed portions of the periphery Vof vthe spongyroll 1 are allowed to re-expand after they Yadvance past the take-offroll 6, until they again reach "the squeeze roll 4, which thencompresses these'portions to a much greater' extent than did the lroll6, thereby expressing the remainder of the water from these portions ofthe roll 1. The/water expressed by the squeeze roll 4 is removedtherefrom Vby-a doctor blade 10, and allowed to iio'w down an inclinedapron 11 intoa drain troughlZ.

At this point in the rotation of the rolll ythesponging cycle ofcompression and expansion starts again.

The squeeze roll 4 and the take-oit roll 6 are both made of `a corrosionresistant, Wear resistant, hard material, such as bronze or steel. Thesqueeze roll -4 is made considerably larger in'diameter than is thetake-off -roll"'6, -in

order tocompress the spongy roll l'to a greater'extent. Driving means(not shown) Imay be peratively connected to thev take-off roll 6 toiin'p'artrotation to the three rolls 1, 4 and 6.

It isr evident thatapparatus embodying the yinvention provides averysimpleand effective means for thickening force which can be-createdbycompression'and expansion fof the spongy roll is. greater thancannormallybe obtained from aconventionalfscreen covered cylinderro1l,`whichjis dependent lupon adiierence in the levels oftheistock.v

Another important advantage y of apparatus Nembodying the invention isthe elimination of a water spray to wash the pulp fibers from thetake-off roll. It is also contemplated that the simple construction ofthis apparatus may enable it to be made portable, thereby providing`other practical advantages.

It will be obvious to those skilled in the art that various changes maybe made Without departing from the spirit of the invention, andtherefore the invention is not limited to what is shown in the drawingand described in the specification, but only as indicated in theappended claims.

What is claimed is:

l. Apparatus for extracting excess liquid from dilute liquid suspensionsof fibers, comprising a massive spongy roll composed of an absorbentresilient material mounted rotatably partially submerged in such asuspension, means for compressing successive portions of the peripheryof the roll as they enter the suspension during rotation of the roll,which portions are allowed to re-expand beneath the surface of thesuspension thereby extracting fibers from the liquid and depositing thefibers on the periphery of the roll, and take-off means mounted inpartially cornpressive contact with said periphery for removing thedeposited fibers from the roll after they have emerged from thesuspension.

2. Apparatus for extracting excess liquid from dilute liquid suspensionof fibers, comprising a massive spongy roll composed of an absorbentresilient material mounted rotatably partially submerged in'such asuspension, a squeeze roll mounted rotatably in engagement with thespongy roll for compressing successive portions thereof as they enterthe suspension, which portions are allowed to re-expand beneath thesurface of the suspension thereby extracting fibers from the liquid anddepositing the fibers on the periphery of the roll, and take-ofi meansmounted in partially compressive contact with said periphery forremoving the deposited fibers from the roll after they have emerged fromthe suspension.

3. Apparatus for extracting excess liquid from dilute liquid suspensionsof fibers, comprising a massive spongy roll composed of an absorbentresilient material mounted rotatably partially submerged in such asuspension, a

squeeze roll mounted rotatably in engagement with the` spongy roll forcompressing successive portions thereof as they enter the suspensionduring rotation of the roll, which portions are allowed to re-expandbeneath the surface of the suspension thereby extracting fibers from theliquid and depositing the fibers on the periphery of the roll, and atake-off roll mounted rotatably in engagement with the spongy roll forremoving the deposited fibers from the spongy roll after they haveemerged from the suspension.

4. Apparatus for extracting excess liquid from dilute liquid suspensionsof fibers, comprising a massive sponge movable through such asuspension, means for compressing successive portions of the sponge asthey enter the suspension, Iwhich portions are allowed to re-expandbeneath the surface of the suspension thereby extracting fibers from theliquid and depositing the fibers on the surface of the sponge, andtake-off means mountedin partially compressive contact with said surfacefor removing the deposited fibers from the sponge after they haveemerged from the suspension.

5. Apparatus for extracting excess liquid from dilute liquid suspensionsof fibers, comprising a massive sponge movable through such asuspension, a squeeze roll mounted rotatably in engagement with thesponge for compressing successive portions thereof as they enter thesuspension, which portions are allowed to re-expand beneath the surfaceof the suspension thereby extracting fibers from the liquid anddepositing the fibers on the surface of the sponge, and take-off meansmounted in partially compressive contact with said surface for removingthe deposited fibers fromA the sponge after they have emerged from thesuspension, l v

6. Apparatus for extracting excess liquid from dilute liquid suspensionsof fibers,comprising a massive sponge movable through such a suspension,a squeeze roll mounted rotatably in engagement with the sponge forcompressing successive portions thereof as they enter the suspension,which portions are allowed to re-expand beneath the surface of thesuspension thereby extracting fibers from the liquid and depositing thefibers on the sponge, and a take-ofi roll mounted rotatably incompressing engagement with the sponge for removing the deposited fibersfrom the sponge after they have emerged from the suspension.

7; Apparatus for .separating excess liquid from dilute liquid fibroussuspensions, comprising a massive spongy roll composed of an absorbentresilient material mounted rotatably partially submerged in such asuspension, a squeeze roll mounted rotatably in compressing engagementwith the spongy roll at approximately the uppen4 level of the suspensionfor compressing successive portions of the periphery of the spongy rollas they enter the suspension during rotation of the roll, which portionsare allowed to re-expand beneath the surface of the suspension therebyextracting fibers from the liquid and depositing the fibers on thespongy roll, and a take-off roll mounted in compressing engagement withthe spongy roll above the upper level of the suspension, said takeoffroll compressing the spongy roll sutiiciently to express a small portionof the liquid absorbed therein to wash the deposited fibers from theperiphery of the spongy roll.

8. The apparatus defined by claim 7, wherein the takeolf roll issmallerin diameter than the squeeze roll, and these rolls are mountedapproximately 270 apart on the periphery of the spongy roll.

9. Apparatus for thickening pulp stock, comprising a massive spongerubber roll mounted rotatably partially submerged in a dilute waterslurry of pulp stock, a squeeze roll mounted rotatably in compressingengagement with the sponge roll at approximately the upper level of theslurry for compressing successive portions of the periphery of thesponge roll as they enter the slurry during rotation of the roll, whichportions are allowed to re-expand beneath the surface of the slurrythereby extracting pulp fibers from the water and depositing the fiberson the sponge roll, a take-off roll mounted in compressing engagementwith the sponge roll above the upper level of the slurry, said take-offroll compressing the sponge roll suiciently to express a small portionof the water absorbed therein to wash the deposited fibers from theperiphery of the sponge roll, and a pair of doctor blades mountedadjacent to the squeeze roll and the take-off roll for removing excesswater and wet pulp fibers, respectively, from these rolls.

l0. The apparatus defined by claim 9, wherein the take-oli roll issmaller in diameter than the squeeze roll, and these rolls are mountedapproximately 270 apart on the periphery of the sponge roll.

11. A method of thickening a thin liquid slurry of fibrous pulp stock,comprising the steps of continuously advancing a massive sponge intosuch a slurry to mmerse successive portions of the sponge therein,continuously compressing said portions of the sponge as they enter theslurry while permitting said portions to reexpand within the slurry,thereby soaking up liquid from the slurry in the interorof the spongeand depositing extracted pulp bers on the surface of the sponge,advancing said vportions of the sponge out of the slurry, and

then removing the deposited fibers from the surface ofy the sponge.

12. A method of thickening a thin liquid slurry of fibrous pulp stock,comprising the steps of continuously advancing a massive sponge intosuch a slurry to immerse successive portions of the sponge therein,continuously compressing said portions of thesponge as they enter theslurry `while permitting said portions to re-expand within the slurry,thereby soaking up liquid from the slurry in the interior of the spongeand depositing extracted pulp bers on the surface of the sponge,advancing said portions of the sponge out of the slurry, and thenpartially compressing said portions of the sponge to express sucentliquid from its interior to wash oi the deposited fibers from itssurface.

References Cited in the le of this patent UNITED STATES PATENTS

1. A APPARATUS FOR EXTRACTING EXCESS LIQUID FROM DILUTE LIQUIDSUSPENSIONS OF FIBERS, COMPRISING A MASSIVE SPONGY ROOO COMPOSED OF ANOBSORBENT RESILIENT MATERIAL MONTED ROTATABLY PARTIALLY SUBMERGED INSUCH A SUSPENSION, MEANS FOR COMPRESSING SUCCESSIVE PORTIONS OF THEPERIPHERY OF THE ROLL AS THEY ENTER THE SUSPENSION DURING ROTATION OFTHE ROLL, WHICH PORTIONS ARE ALLOWED TO RE-EXPAND BENEATH THE SURFACE OFTHE SUSPENSION THEREBY EXTRACTING FIBERS FROM THE LIQUID AND DEPOSITINGTHE FIBERS ON THE PERIPHERY OF THE ROLL, AND TAKE-OFF MEANS MONTED INPARTIALLY COMPRESSIVE CONTACT WITH SAID PERIPHERY FOR REMOVING THEDEPOSITED BIERES FROM THE ROLL AFTER THEY HAVE EMERGED FROM THESUSPENSION.